Laser PSU and hot wire questions

[StevoLaser]

Hey guys,

My laser was in the middle of making my first real thing, just trying to cut through 1/8" MDF. On the second pass, I heard an audible pop and the laser stopped lasing... so I hit the e-stop and powered down.

Visually, the connections from laser tube to PSU looked good. I went through the power on process and it sounds as though the fan on the laser power supply isn't coming on. I am happy to open up the PSU to check the fuse, but:

How long after using the power supply should one wait before opening up the unit? I've got the 20W~45W PWM CO2 Laser Power Supply (AC110V)
How long after using the laser should one wait before touching the wires going to the tube?

And I have another question... People insulate the heck out of their "hot" wire and hot wire connections, right? But the return wire goes to the ammeter which is on the control panel and people don't usually insulate those connections much.. Why is that?

Thanks

Steve

[StevoLaser]

Hey Marco,

Is it OK for me to open up the PSU and check the fuse?

Steve

[Tech_Marco]

Sure, go ahead. If you hear pop sound, most likely the power transistors cracked

Marco

[StevoLaser]

Hey Marco,

I got the PSU open enough to see that the fuse had blown. I'll go to Radio Shack today and buy a new T6.3AL250V and see how it goes and I'll let ya know.

Steve

[StevoLaser]

Hey Marco,

I went to Radio Shack yesterday and bought a pack of 6.3Amp slow burn 250V fuses. I installed it, screwed it back together and reconnected wires to laser. Upon power up, the fan came on and there was a sound of something arc'ing inside the PSU. The arc sound stopped in a second, but the fan stayed on. I pressed my test fire button but the laser did not fire.

It had been working.

"W" is jumpered to "Gnd"
System was set to fire on "L"
Water pump is working

20W~45W PWM CO2 Laser Power Supply (AC110V)

What is next?

Steve

[Tech_Marco]

You may need to get RMA and return it for repair.
It is still within 6months warranty?
I think you may need to pay attention on the wire connection as it seems losing wire, either HV or return ground got lose and pop the LPSU. The transistors are dead in most case when you heard 'pop' sound


Marco